The lobbying clout of doctors is being tested by a 27 percent Medicare fee cut that Congress may be unable to reverse as lawmakers grapple with proposals to pare the deficit by $1.2 trillion. Doctors hope a congressional debt panel will delay the reduction, as Congress has done often in the past decade. If lawmakers agree, the cost – $22 billion in 2012 or more than $300 billion in a decade – may be offset by tax increases and budget reductions for other government programs.